Oliver and Sheila Lawn both worked at Bletchley Park in Buckinghamshire, the
very secret wartime code breaking establishment. It was called the Government
Communications Headquarters (GCHQ). All the work done at Bletchley Park
remained Top Secret for some 30 years after the war, and only then were Oliver
and Sheila able to talk about their work there.

Oliver Lawn was recruited for Bletchley Park by Gordon Welchman in July 1940.
He had just completed a Mathematics Degree at Jesus College, Cambridge, and had
expected then to be called up into the Army, as many of his contemporaries were
being. Gordon Welchman, a Cambridge Mathematics Don, had been recruited for
Bletchley at the beginning of the War in September 1939, along with other
Oxford and Cambridge Dons, who included Alan Turing. In July 1940 Welchman was
recruiting other Mathematicians, and Oliver was one of these.

He joined a team with Welchman in Hut 6 at Bletchley Park, which was concerned
with breaking the Enigma Codes used by the German Army and Air Force. ['The
Enigma Codes used by the German Navy were different, and were broken by a quite
different group of people, in Hut S.] He remained in Hut 6 for 5 years, until
September 1945.

The methods mostly used for breaking these Enigma Codes were by guessing
`cribs' - that is, guessing what some part of an encoded message actually said,
in German. This was of course only possible for `routine' messages such as
daily weather reports or forecasts, which often began - or ended - with a
standard phrase or a record of the time of sending (eg `Wettervorhersage' or
`nullsechsnullnull' _ `0600' hours). By aligning such phrases with the encoded
text which was received over the radio in Morse code, pairs of text letters and
encoded letters were thrown up, and these were grouped into `menus' looking
rather like diagrams of Euclidean Geometry. The menus were then tested by large
machines called `Bombes', seeking the correct setting of the Enigma machine at
which the message had been encoded - the daily `key'. When this `key' had been
found, all the messages on that key, and on that day, could be decoded. Keys
changed daily at midnight, and each day's key had to be separately discovered.
There were separate daily keys for different parts of the German Services. The
total number of possible Keys was 150 million million million.

Success in breaking the keys varied, but generally most of the keys were broken
for most days.

Sheila was recruited for Bletchley Park in July 1943 when she was in the middle
of a Modern Languages Honours Degree Course (French and German) at Aberdeen
University. She had earlier been `reserved' from call-up as a potential
teacher, but decided that she must abandon this reservation and join the War
effort. She worked in a part of the Naval Section at Bletchley Park, in Block
B. Her main work was to decode and then translate 3-letter codes used by German
Coastal Batteries and Radar Stations located around the Channel coasts. She
continued at Bletchley until the end of the War in September 1945.

Early in his time at Bletchley Oliver had joined the Scottish Reels Club, run
by Hugh Foss, who was Head of the BP Japanese Section ( though, of course, at
the time he did not know this). In due course, after she arrived in 1943,
Sheila joined this Club. She was first attracted by Oliver's excellent dancing,
and then by Oliver himself. The attraction was mutual, and they soon started
going out together, as far as their different shift patterns permitted.

After the War, when they both left Bletchley Park, Oliver had to find a job,
and he joined the Administrative Home Civil Service in 1946. Sheila, meanwhile,
had to complete her interrupted studies. Since there was at that time no scope
for travelling abroad (and what use would a Language Degree be without it ?),
she changed her course to a General Degree at Aberdeen followed by a Social
Science Diploma at Birmingham University.

Then, in May 1948, Oliver and Sheila got married. They lived in London. Oliver
worked in several Government Departments, including latterly the Department of
the Environment. Sheila initially had a Personnel job with London Transport.

They had 2 sons, David and Richard, and now have 4 grandchildren. On retirement
in 1978 they moved to Sheffield, and have been involved there with a number of
voluntary and charitable activities.

Oliver and Sheila first revisited Bletchley Park in 1996, 50 years after they
had left, and they have made many subsequent visits. They have also, since
secrecy was lifted, given many talks to groups, and also interviews on TV,
Radio and for Newspapers, about their wartime work. They are delighted to see
the continuing public interest in Wartime code breaking - `Top Secret' for so
long - and to see the large numbers of people now visiting Bletchley Park.